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HOMEOSTASIS. Thermoregulation. Louis Chow. What is it?. Significance?. Enables organisms to explore inhospitable environments. Homeostasis. The ability of the body to maintain a constant internal environment despite fluctuations in both the body’s activities and the external environment

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Louis chow

HOMEOSTASIS

Thermoregulation

Louis Chow


Homeostasis

What is it?

Significance?

Enables organisms to explore inhospitable environments

Homeostasis

  • The ability of the body to maintain a constant internal environment despite fluctuations in both the body’s activities and the external environment

  • Consists of specific values which are considered as normal


Negative feedback mechanism

Negative Feedback Mechanism...


Negative feedback mechanism1

Negative feedback mechanism

  • Receptors detects a stimulus (external or internal change).

  • Communication between the receptor and the effector(through a control centre).

  • Effector brings about the response to restore balance.

  • When the response is enough to return the body back to its normal state, the receptor is turned off.


Why control body temperature

Why control body temperature?

  • Independence from changing environments

  • Affects the rate of metabolic reactions

  • Sensitivity of enzymes


Ectotherms

Ectotherms

Ectotherms:

  • Fish, amphibians, reptiles etc.

  • Body temperature is greatly dependent on the external temperature

  • Variable metabolic rate

  • Activity levels determined by external environment


Behavioral responses

Behavioral responses

  • Voluntary responses

  • Temperature too cold: cuddling, put on more clothes, eating, more muscular activities, move closer to heat sources, e.g the Sun

  • Temperature too hot: Less clothing, cool drinks, find shades, body orientation


Endotherms

Endotherms

Endotherms:

  • Mammals and birds

  • Body temperature is less dependent on the external temperature

  • High metabolic rate

  • Possess thermoregulating mechanisms


Physiological adaptions

Physiological adaptions

  • controlled by the thermoregulatory centre in the hypothalamus.

  • Receptors in the hypothalamus itself(blood temperature, the core temperature)

  • Skin receptors (the external temperature)

  • Also controlled by the cerebral cortex -- Voluntary actions


Heat gain vs heat loss

Heat gain vs heat loss


Heat exchange between organisms and their surroundings

Heat Exchange between organisms and their surroundings:


Core temperature and skin temperature

Core temperature and skin temperature

  • http://www.youtube.com/watch?v=Vlp_NHuC0rw


Thermoregulation

Thermoregulation

Hot:

Cold:

Increase heat gain

decrease heat loss

  • decrease heat gain

  • Increase heat loss


Pilorelaxation and piloerection

Pilorelaxation and Piloerection

Relaxation of erector muscle Contraction of erector muscle


Vasodilation and vasoconstriction

Vasodilation and Vasoconstriction

Hot:

Cold:

Skin arterioles constrict

Sphincter muscles contract

Shunt vessels dilate

Blood flow to skin capillaries decreased

  • Skin arterioles dilate

  • Sphincter muscles relax

  • Shunt vessels constrict

  • Blood flow to skin capillaries increased


Sweat production

Sweat production

Hot:

Cold:

Inhibition of sweat glands

Decreased sweat production

  • Activation of sweat glands

  • Increased sweat production


Extreme temperatures

Extreme temperatures

Hypothermia

Hyperthermia

Core temperature higher than 38.5 degrees Celsius

Adverse effects by drugs

Heat stroke

Dizziness, confusion

  • Core temperature falls below 35 degrees Celsius

  • Enhanced by alcoholic effects

  • Amnesia, death


Preventing hypothermia

Preventing hypothermia

  • Wear more clothes!!

  • Avoid diving in cold water

  • Go closer to heat sources


Preventing hyperthermia

Preventing hyperthermia

  • Find shades

  • Avoid excess exercise


What might come in the exam

What might come in the exam..

  • Where is the best place to take a temperature of a person?

  • Define evaporative heat loss.

  • Describe and explain a way of losing heat.


The end

THE END

Thank you!


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